Sensor and Method for Producing a Sensor

ABSTRACT

A sensor comprises a sensor element configured to provide a sensor signal representing at least one measurand detected by the sensor element, an electrical circuit configured to process the sensor signal to form a data signal, a photovoltaic cell configured to provide electrical energy for the sensor element and the electrical circuit, and a housing, in which the sensor element, the electrical circuit and the photovoltaic cell are positioned, the housing including a recess in which the photovoltaic cell is positioned, and a rim surrounding the recess and protruding beyond the photovoltaic cell. A method is also provided

PRIOR ART

The present invention relates to a sensor and to a method for producinga sensor.

A component can be operated in an energy self-sufficient manner when anenergy source or a device for recovering energy is integrated into thecomponent.

US 2011/0169554A1 describes an integrated solar-operated component.

DISCLOSURE OF THE INVENTION

On this basis, a sensor and a method for producing a sensor according tothe main claims will be presented with the present invention.Advantageous embodiments will emerge from the respective dependentclaims and the following description.

In order to place a photovoltaic cell in a housing, the photovoltaiccell may be arranged in an indentation, set back from a surface of thehousing. Due to the set-back arrangement, the photovoltaic cell isbetter protected against damage than if the photovoltaic cell werearranged flush with the surface. In particular, lateral edges of thephotovoltaic cell, at which a sensitive semiconductor material may beexposed, are well protected in the indentation against damage, such ascorrosion or rupture.

A sensor is presented that has the following features:

an electronic component or sensor element for providing a sensor signalwith use of electrical energy, wherein the sensor signal represents atleast one measurand detected by the sensor element;an electrical circuit for processing the sensor signal to form a datasignal with use of electrical energy;a photovoltaic cell for providing the electrical energy for the sensorelement and the electrical circuit, wherein the; anda housing, by which the sensor element, the electrical circuit and thephotovoltaic cell are accommodated, wherein the housing has a recess, inwhich the photovoltaic cell is arranged, wherein a rim of the housingsurrounding the recess protrudes beyond the photovoltaic cell.

An electronic component may be in particular an ASIC, which for exampledirectly measures a temperature. A sensor element may be amicroelectromechanical (MEMS) sensor element. The sensor element may bedesigned to detect at least one measurand. The measurand may be aphysical variable. The measurand may be a chemical variable. A sensorsignal may be an electrical signal. In particular, the sensor signal maybe an analog signal. An electrical circuit may be an integrated circuit.A data signal may be a digital signal in particular. The electricalcircuit may be designed to transmit the data signal via a communicationprotocol to a receiver. A photovoltaic cell may be a back-contact solarcell. Then, electrical contacts of the photovoltaic cell may becontacted from a light-insensitive side of the photovoltaic cell. Thephotovoltaic cell may also be a solar cell with front-side contact andrear-side contact. Then, the front-side contact may be contacted on thelight-sensitive side of the solar cell. A housing may be a protectivecasing. The housing may be fluid-tight. The housing may be constructedfrom one or more different materials. The rim of the housing may runperipherally around the recess in a closed manner. The rim may protrudebeyond the light-sensitive surface of the photovoltaic cell. A spacelocated between the surface of the photovoltaic cell and an outersurface of the rim, i.e. a region of the recess adjacent to thelight-sensitive surface of the photovoltaic cell and not filled by thephotovoltaic cell, may be material-free, i.e. filled for example withambient air, or may be filled with a protective medium. The recess maybe formed as a blind bore in a material forming the housing. A depth ofthe recess, i.e. a distance between a base of the recess and an edge ofthe rim of the housing adjacent to a side wall may be greater than athickness of the photovoltaic cell. The rim of the housing may be formedfrom a printed circuit board material or from a potting compound. Inthis way the rim may be formed from a hard material, which may shieldthe photovoltaic cell against external influences.

A transition region between the photovoltaic cell and the housing may besealed using a protective medium. The transition region may be arrangedat an edge that connects the light-sensitive side of the photovoltaiccell to the light-insensitive side of the photovoltaic cell. Aprotective medium may be a substance that is introduced into thetransition region and cures in the transition region. The protectivemedium may also be permanently flexible, for example in order tocompensate for thermal stresses. The protective medium may betransparent. Then, the protective medium may also be arranged over theentire surface of the light-sensitive side of the photovoltaic cell. Byway of example, a protective medium may be a protective gel, protectivepaint or a melt.

The sensor element and alternatively or in addition the electricalcircuit may be arranged on a light-insensitive side of the photovoltaiccell. The sensor element and/or the electrical circuit may be arrangedin separate semiconductor chips. The semiconductor chips may be placedon the rear side of the photovoltaic cell, before the housing is formed.A printed circuit board with conductive tracks may be arranged betweenthe photovoltaic cell and the sensor element and/or the electricalcircuit.

The housing may be formed at least in part by a potting compound. Thesensor element and alternatively or additionally the electrical circuitmay be potted in the potting compound. A potting compound by way ofexample may be a plastic that completely surrounds the sensor elementand alternatively or additionally the electrical circuit and protectsagainst external influences. The potting compound may be molded in afemale tool to provide the housing. The potting compound may bethermoplastic.

Electrical conductive tracks may be arranged in the rim of the housing.The photovoltaic cell may be contacted electrically by the conductivetracks in the rim. The rim may have a protrusion beyond thelight-sensitive side of the photovoltaic cell. Part of thelight-sensitive side of the photovoltaic cell may thus be covered by therim. In this case at least one electrical connector of the photovoltaiccell may be contacted on the light-sensitive side.

The photovoltaic cell may be surrounded (embedded) by the rim in such away that there is contact at least on all sides with the surfaces of thephotovoltaic cell, at least in sub-regions of the surfaces. An edge ofthe photovoltaic cell may be embedded in the rim. The edge may becompletely surrounded. The photovoltaic cell may thus be protectedparticularly well by the housing. The photovoltaic cell may be cast inor encapsulated by injection molding in order to embed the edge in therim. A printed circuit board can be constructed from a number of layers,wherein at least one layer has a cutout that is large enough for thephotovoltaic cell. A cover layer may have a smaller cutout, such thatthe cover layer protrudes beyond the photovoltaic cell at the edge. Thephotovoltaic cell may also be placed over the cutout in the cover layerand potted with the electrical circuit and the sensor element from thelight-insensitive side.

The housing may have electrical connectors on the rim and alternativelyor additionally on a rear side opposite the recess. Connectors may beformed as an interface of the electrical circuit. The electricalconnectors may be formed via feedthroughs, or what are known as vias, inthe housing. The connectors may be formed identically on both sides ofthe housing. Then, the connectors can be accessed irrespective of aposition of installation. By way of example, a function of the sensorcan be checked by means of the connectors.

The electrical circuit may have an antenna for wirelessly transmittingthe data signal. Due to a wireless data transmission, the sensor may beplaced at any point within a range of a receiver. Cables can thus bespared.

The sensor may have an energy store for the electrical energy, whereinthe energy store is surrounded by the housing. An energy store by way ofexample may be an accumulator or a capacitor. Energy from thephotovoltaic cell can be stored in the energy store when there is anenergy excess. If there is an energy deficiency, the sensor may beoperated with use of the energy in the energy store. By way of example,the sensor may then detect data even in darkness.

A method for producing a sensor is also presented, wherein the methodcomprises the following steps:

providing a sensor element, an electrical circuit and a photovoltaiccell, wherein the photovoltaic cell is connected to the electricalcircuit and the electrical circuit is connected to the sensor element;andarranging the sensor element, the electrical circuit and thephotovoltaic cell in a housing, wherein the photovoltaic cell isarranged in a recess in the housing, wherein a rim of the housingsurrounding the recess protrudes beyond the photovoltaic cell.

In the provision step a plurality of arrangements formed of a sensorelement, an electrical circuit and a photovoltaic cell can be provided,and in the arrangement step the plurality of arrangements can bearranged in a common housing. The method may comprise a separation step,in which the housing is separated into a plurality of sub-housings,wherein each sub-housing has an arrangement. Manufacturing costs andtime can be saved simultaneously by means of a production of a pluralityof sensors.

The invention will be explained in greater detail hereinafter by way ofexample on the basis of the accompanying drawings, in which:

FIG. 1 shows a schematic illustration of a sensor in accordance with anexemplary embodiment of the present invention;

FIG. 2 shows an illustration of a sensor with sealed photovoltaic sideedges in accordance with an exemplary embodiment of the presentinvention;

FIG. 3 shows an illustration of a sensor with photovoltaic cell sideedges embedded in a printed circuit board in accordance with anexemplary embodiment of the present invention;

FIG. 4 shows an illustration of a sensor with photovoltaic cell sideedges embedded in a printed circuit board and with a cover in accordancewith an exemplary embodiment of the present invention;

FIG. 5 shows an illustration of a sensor with a housing formed frompotting compound and printed circuit board material in accordance withan exemplary embodiment of the present invention;

FIG. 6 shows an illustration of a sensor with a housing formed frompotting compound in accordance with an exemplary embodiment of thepresent invention;

FIG. 7 shows a flow diagram of a method for producing a sensor inaccordance with an exemplary embodiment of the present invention; and

FIG. 8 shows an illustration of a plurality of sensors embedded togetherin accordance with an exemplary embodiment of the present invention.

In the following description of preferred exemplary embodiments of thepresent invention, like or similar reference signs are used for thesimilarly acting elements illustrated in the various figures, wherein arepeated description of these elements is spared.

FIG. 1 shows a schematic illustration of a sensor 100 in accordance withan exemplary embodiment of the present invention. The sensor 100 has asensor element 102, an electrical circuit 104, a photovoltaic cell 106,and a housing 108. The sensor element 102 is designed to provide asensor signal with use of electrical energy. The sensor signalrepresents at least one measurand detected by the sensor element 102.The electrical circuit 104 is connected to the sensor element 102 and isdesigned to process the sensor signal to form a data signal with use ofelectrical energy. The photovoltaic cell 106 is designed to provide theelectrical energy for the sensor element 102 and the electrical circuit104 and is connected to the electrical circuit 104. The sensor element102, the electrical circuit 104 and the photovoltaic cell 106 arearranged in the housing 108. The housing 108 has a recess 110, in whichthe photovoltaic cell 106 is arranged. A rim 112 of the housing 108,which rim surrounds the recess 110, protrudes beyond the photovoltaiccell 106, such that a light-sensitive surface of the photovoltaic cell106 is set back behind a surface of the housing 108. In accordance withthe exemplary embodiment shown in FIG. 1, the light-sensitive surface ofthe photovoltaic cell 106 is not covered by the housing 108 or anothercover layer or protective layer. There is thus a free space between therim regions of the recess 110 protruding beyond the light-sensitivesurface of the photovoltaic cell 106. In accordance with an alternativeexemplary embodiment the light-sensitive surface of the photovoltaiccell 106 may be covered by a cover layer. By way of example, the recess110 may be filled with a transparent material, which may terminate flushwith an outer surface of the rim 112, in FIG. 1 the downwardly pointingsurface of the rim 112.

FIG. 1 shows an exemplary embodiment of a design for integration and forprotection of one or more photovoltaic cells 106 in sensor systems andsensors 100.

A sensor 100 of this type can be used for example in conjunction withthe “Internet of Things” (IoT), which is described as one of the mostimportant future developments in information technology. As a result ofthe Internet of Things, not only do humans have access to the Internetand not only are they linked thereby, but devices are also linked to oneanother via the Internet. The examples already technically realizedinclude washing machines with Internet access, which automatically startthe washing process when electricity prices are low. Another examplewould be a linked refrigerator, which automatically reorders the removedfood. Another region of the Internet of Things is targeted at productionand domestic automation with autonomous sensors 100, which obtain theirenergy either from batteries and/or with energy harvesters such asphotovoltaic cells 106, thermoelectric generators or from vibrations.Sensors 100 of this type may use elements 102 from the field of consumerelectronics, such as sensors 102 for smartphones, for examplegyroscopes, acceleration sensors, pressure sensors or microphones. Dueto be economically available sensor elements 102, sensors 100 can beproduced at low overall cost. By way of example, a sensor 100 fordetection of the window position at a window frame or a moisture sensorfor mildew detection behind a cupboard on the wallpaper thus can beproduced economically. Sensor modules 100 for the Internet of Things(overall size a few cm³) may contain not only at least one sensor 102for the detection of a physical/chemical variable, but may alsointegrate a processor 104, a radio module, an energy store and an energyharvester 106 in a small installation space.

In the approach presented here a photovoltaic cell 106 is integrated ina small autonomous sensor system 100 with a base area of a few squarecentimeters, for example with a base area of less than 10, 5 or 3 squarecentimeters, such that the edges of the photovoltaic cell 106 areprotected and a vertical peripheral protrusion 112 of the housing 108beyond the active surface of the solar cell 106 protects this againstmechanical influences, at least in part.

Due to the integration of the photovoltaic cell 106 in the sensor module100, the lateral edges are protected against external influences and atthe same time the active surface of the photovoltaic cell 106 isprotected against mechanical stresses by an at least partially verticalperipheral protrusion 112 of the housing.

FIG. 2 shows an illustration of a sensor 100 with sealed photovoltaiccell side edges in accordance with an exemplary embodiment of thepresent invention. The sensor 100 may correspond to the sensor shown inFIG. 1. Additionally to FIG. 1, the housing 108 here has a first housingpart 200 formed from a printed circuit board material 202 and a secondhousing part 204 formed from a potting compound (molding compound) 206.The recess 110 with the photovoltaic cell 106 is arranged in the firsthousing part 200. In this exemplary embodiment the recess 110 has beenproduced by means of material-removing machining. The photovoltaic cell106 is formed as a back-contact cell and is adhesively bonded to contactpads 208 in the recess 110 with use of conductive adhesive. Thephotovoltaic cell 106 may also be soldered to the contact pads 208 withuse of solder. A gap 210 extends around the photovoltaic cell 106between the rim 112 and the photovoltaic cell 106. In order to protectthe sensitive photovoltaic cell side edges, the gap 210 is sealed with aprotective gel 212. The photovoltaic cell side edges can be protected bythe protective gel 212. Optionally, the entire remaining recess 110 canbe sealed with the protective gel 212. Then, the light-sensitive surfaceof the photovoltaic cell 106 can also be protected.

Conductive tracks 214 are integrated in the first housing part 200.Inter alia, the first housing part 200 has electrical feedthroughs(vias) 216. The electrical feedthroughs 216 may extend completelythrough the first housing part 200. By way of example, an electricalfeedthrough 216 may extend from the outer surface of the rim 212 to asurface of the first housing part 200 adjacent to the second housingpart 204. Further feedthroughs 213 may extend from the surface of thefirst housing part 200 adjacent to the second housing part 204 as far asthe contact pads 208 of the photovoltaic cell 106. A conductive track214 may extend parallel to an interface between the first housing part200 and the second housing part 204 in a portion of the first housingpart 200 spanning the light-insensitive side 105 of the photovoltaiccell 106. A conductive track 214 of this type may be electricallyconnected to contacts arranged at the interface between the firsthousing part 200 and the second housing part 204 in order to contact thesensor element 102 and the electrical circuit 104.

The conductive tracks 214 are embedded in part in the printed circuitboard material 202. The sensor element 102 and the electrical circuit104 are arranged on a rear side of the first housing part 200 oppositethe recess 110. The sensor element 102 and the electrical circuit 104are formed as integrated components (ASICS, MEMS) based on asemiconductor material and are connected via contact wires (wire bonds)218 to the conductive tracks 214 of the first housing part 200.

The second housing part 204 is formed as a protective sleeve around thesensor element 102 and the electrical circuit 104. The sensor element102 and the electrical circuit 104 are embedded in the second housingpart 204. The rim 112 is defined by the recess 110 on one side and sidesurfaces of the housing 108 on the other side. The rim 112 is flush withthe side surfaces. Feedthroughs 216 are likewise arranged in the rim 112and reach as far as a surface of the housing 108.

FIG. 3 shows an illustration of a sensor 100 with photovoltaic cell sideedges embedded in a printed circuit board 202 in accordance with anexemplary embodiment of the present invention. The sensor 100corresponds to the sensor in FIG. 3. In contrast to FIG. 3, here thereis no gap between the rim 112 and the photovoltaic cell 106. Here thelateral edge of the photovoltaic cell 106 is embedded in the printedcircuit board material 202 of the first housing part 200. The rim 112surrounds the edge completely and extends in a rim region over thephotovoltaic cell 106 on the light-sensitive side 105 of thephotovoltaic cell 106. The lateral protection of the solar cell 106prevents influences, such as moisture or mechanical damage, on the edgesof the photovoltaic cell 106, at which the sensitive semiconductorregion is located. By way of example, it is thus possible to preventmoisture from short-circuiting the sensitive p-n semiconductor junction.

In FIG. 3 the photovoltaic cell 106 is integrated in the printed circuitboard 202 by means of embedding. In other words FIG. 3 shows a furthervariant of the approach presented here. The photovoltaic cell 106 isintegrated directly in the printed circuit board 202 by means ofembedding technology. In this case the lateral protection and theprotrusion 112 are provided using printed circuit board materials 202.The embedding technology may also be used for electrical contacting ofthe chips 102, 104 in the printed circuit board 202. For the integrationof a photovoltaic cell 106 in the printed circuit board 202, not only isgood edge protection thus provided, but it is thus also possible toelectrically contact photovoltaic cells 106 with contacts 208 on bothsides, i.e. on the underside and the upper side. As is the case with thepreviously described variant, a gel 212 can also be filled here into thecavity 110 for protection. A lateral distance of the photovoltaic cell106 from the printed circuit board 202 as in FIG. 2 is not providedhere.

The protrusion 112 of the housing 108 beyond the base area of thephotovoltaic cell 106 provides a number of advantages. The cell area ofthe active photovoltaic cell is protected against mechanical influencescaused by placement on surfaces. The lateral protrusion 112 togetherwith the cell area of the photovoltaic cell forms a cavity 110, in whichan additional, for example transparent, protection medium at 212, suchas gel, paint or melt, can be easily deposited for the active surface ofthe photovoltaic cell 106. If the lateral protrusion 112 is provided bya printed circuit board 202, electrical contacts 216 can thus be guidedoutwardly at the same time.

The vertical protrusion 112 may also envelope or cover the activesurface of the photovoltaic cell 106 at the sides to a certain extent.If in this case a printed circuit board material 202 is used (embeddingof the PV cell 106 in a printed circuit board 202), it is thus possibleto contact a photovoltaic cell 106 both on the front side and on therear side using standard printed circuit board technology, asillustrated in FIG. 3. This is advantageous since photovoltaic cells 106with a contact on both the front side and rear side are widespread andeconomical.

In FIG. 3 the photovoltaic cell 106 is thus integrated in a monolayer ormulti-layer printed circuit board 202. Here the photovoltaic cell 106 isglued for example in a blind bore 110 located in the printed circuitboard 202. The gap 210 results here from a necessary distance due to aprocess tolerance and is filled after the gluing, possibly withprotective gel 212.

In accordance with an exemplary embodiment FIG. 3 shows a variant of thedesign of an autonomous sensor system 100. Here an indentation is milledor drilled into the printed circuit board 202, into which indentationthe photovoltaic cell 106 is subsequently introduced by means ofadhesive, for example conductive adhesive for the contacts 208. Due tothe process tolerances, a lateral distance 210 from the printed circuitboard 202 is provided, which can then be sealed by way of example usinga protective gel 212. This variant enables simple contacting of thephotovoltaic cell 106, which has the two contacts 208 on the rear side,i.e. the side 105 of the photovoltaic cell 106 not facing toward a lightsource. It is also advantageous that electrical contacts 216 can beguided through the printed circuit board 202 by means of standardtechnologies of printed circuit board manufacturers. Both sides of theprinted circuit board 202 can thus be interconnected, whereby a simplecontacting of the system 100 from outside is possible.

FIG. 4 shows an illustration of a sensor 100 with photovoltaic cell sideedges embedded in a printed circuit board 202 and with a cover 400 inaccordance with an exemplary embodiment of the present invention. Thesensor 100 corresponds to the sensor in FIG. 3.

In contrast to FIG. 3, the second housing part 204 is formed here as acover 400 made of metal or plastic. The cover 400 represents analternative protection for the sensor element 102 and the electricalcircuit 104. The cover 400 can be used instead of the molding compound.The cover 400 may be fitted onto the peripheral outer rim of the printedcircuit board 202, such that a rim of the cover 400 terminates flushwith a rim of the printed circuit board 202. The cover 400 surrounds theelements 102, 104 arranged on the printed circuit board 202. Theelements 102, 104 are connected via bond wires to contacts of theprinted circuit board 202.

FIG. 5 shows an illustration of a sensor 100 with a housing 108 formedfrom potting compound 206 and printed circuit board material 202 inaccordance with an exemplary embodiment of the present invention. Thesensor 100 corresponds to the sensor in FIG. 3. In contrast to FIG. 3the printed circuit board material 202 lies on the edge of thephotovoltaic cell 106 only on the front side 105, i.e. thelight-sensitive side 105 of the photovoltaic cell 106. The side surfaceand rear side of the photovoltaic cell 106 are embedded in pottingcompound 206. The first housing part 200 formed from the printed circuitboard material 202 consists here of a ring running around thephotovoltaic cell 106, said ring forming the rim 112 and at least partof the recess 110. A further part of the recess 110, which in accordancewith this exemplary embodiment is filled completely by the photovoltaiccell 106, is formed by the potting compound 206. The photovoltaic cell106 is aligned with the ring formed by the housing part 200, such thatthe photovoltaic cell is completely closed on the light-sensitive sideof the photovoltaic cell 106 by the part of the recess 110 formed by thering. In accordance with this exemplary embodiment the light-sensitiveside of the photovoltaic cell 106 and the ring formed by the housingpart 200 overlap, such that a peripheral rim region of thelight-sensitive side of the photovoltaic cell 106 is carried by thehousing part 200. Before the potting compound 206 is applied, thephotovoltaic cell 106 is connected with feedthroughs 116 in the firsthousing part 200. Furthermore, a further printed circuit board 500 withstructures for rewiring is arranged on the rear side of the photovoltaiccell 106, on which the sensor element 102 and the electrical circuit 104are wired. The photovoltaic cell 106 is connected to the electricalcircuit 104 via the further printed circuit board 500. The sensorelement 102 and the electrical circuit 104 are embedded with the furtherprinted circuit board 500 in the potting compound 206.

In other words FIG. 5 shows a hybrid solution formed of printed circuitboard 202 and molding compound 206. The ASICS/MEMS sensors 102, 104 areembedded with the conductive tracks 500 and the wire bonds 218 and therear side of the PV cell 106 in the molding compound 206. Electricalvias 216 penetrate the rim 112 of the printed circuit board 200. Therecess 110 can be filled optionally with protective gel. The protectivefunction may be ensured in part by printed circuit board material 202and in part by molding compound 206. In this variant the rewiring 500 isperformed on the solar cell 106, and the printed circuit board 200 orthe printed circuit board frame 112 serves merely to guide out theelectrical contacts 216 for functionality tests. The solar cell 106 issurrounded here laterally by molding compound 206, and the protrusion112 is provided by printed circuit board material 202. Here, protectivematerial 212 may also be introduced optionally into the cavity 110.

FIG. 6 shows an illustration of a sensor 100 with a housing 108 formedfrom potting compound 206 in accordance with an exemplary embodiment ofthe present invention. The sensor 100 corresponds to the sensor in FIG.5. In contrast to FIG. 5, the housing 108 here is formed in one pieceand completely from potting compound 206. The photovoltaic cell 106 isembedded at the rear side and at the edge in the potting compound 206.As in FIG. 5 the sensor element 102 and the electrical circuit 104 arearranged on the structure for rewiring 500 having conductive tracks 214,which is secured and wired on the rear side of the photovoltaic cell106. U-shaped cast-in feedthroughs 600 connect a front side 105 of thesensor 100 to a rear side of the sensor 100 and the photovoltaic cell106. The feedthroughs 600 run through the rim 112, behind the sidesurfaces of the sensor 100 to enlarged contact surfaces 602 on the rearside of the sensor 100. In other words FIG. 6 shows a photovoltaic cell106 encased by molding compound 206. Here, the protection is ensured bymolding compound 206 and not by a printed circuit board. The rewiring500 of the sensors 102 may be performed directly on the solar cell 106.From a technological viewpoint, this variant may be provided for exampleby film molds, with which molding is performed from above and below atthe same time. A tool may be provided on the underside, which toolexposes the photovoltaic cell 106, as indicated. Electrical contacts 602may be guided outwardly, for example by means of mold vias 600. Aprocess-induced lateral distance between the photovoltaic cell 106 andthe molding compound 206 as in FIG. 2 is not provided here.

FIG. 7 shows a flow diagram of a method 700 for producing a sensor 100in accordance with an exemplary embodiment of the present invention. Themethod 700 has a provision step 702 and an arrangement step 704. In theprovision step 702 a sensor element, an electrical circuit and aphotovoltaic cell are provided, wherein the photovoltaic cell isconnected to the electrical circuit and the electrical circuit isconnected to the sensor element. In the arrangement step 704 the sensorelement, the electrical circuit and the photovoltaic cell are arrangedin a housing, wherein the photovoltaic cell is arranged in a recess inthe housing and a rim of the housing surrounding the recess protrudesbeyond the photovoltaic cell.

FIG. 8 shows an illustration of a plurality of sensors 100 embeddedtogether in accordance with an exemplary embodiment of the presentinvention. The sensors 100 may correspond to one of the exemplaryembodiments described here. The sensors 100 are arranged in a grid.Here, by way of example, nine identical sensors are arranged in threerows and three columns. Each sensor 100, similarly to the sensorillustrated in FIG. 1, has a sensor element 102, an electrical circuit104, a photovoltaic cell 106 and a housing 108. The housing 108 isapproximately square here. Each photovoltaic cell 106, which likewiseare approximately square, is arranged centrally in the housing 108, suchthat the rim 112 protrudes beyond the photovoltaic cell 106, around saidcell, in order to protect said cell. The sensor element 102 and theelectrical circuit 104 are arranged adjacently in the housing 108. Thesensor element 102 and the electrical circuit 104 are wired to oneanother and are arranged in another plane above the photovoltaic cell106. The housing 108 surrounds the photovoltaic cell 106 at least bymeans of the rim 112 and surrounds the sensor element 102 and theelectrical circuit 104 completely.

The housing 108 may be formed as a one-piece overall housing for allsensors 100 together in a multi-cavity tool. The housings 108 may alsobe formed individually. In the case of a multi-cavity tool, thephotovoltaic cell 106, the sensor element 102 and the electrical circuit104 may be arranged with use of a film 800. The film 800 may be mountedoutside the multi-cavity tool and then inserted with all components intothe multi-cavity tool in order to be encapsulated with potting compound206 by injection molding.

In other words, FIG. 8 shows an array arrangement of photovoltaic cells106 on a temporary substrate 800. The molding regions from the upperside 802 and from the underside 804 are also illustrated. The temporarysubstrate may be a film 800, for example. Each photovoltaic cell 106 maybe arranged with the MEMS/ASIC 102, 104 and wire bonds 218 on the film800. Saw lines 806, along which the sensors 100 are separated, extendbetween the sensors 100. In order to mold the molding compound 206, thetool may reproduce contours from above 802 and from below 804 in thesensors 100. The lateral mold protection can be provided by arrangingthe photovoltaic cells 106 on a temporary substrate 800 (for exampleadhesive film) in an array prior to the molding, as illustrated in FIG.8. This array is then overmolded and the individual sensor elements 100are ultimately processed by the subsequent separation along the sawlines 806 (sawing).

The approach presented here may be used for (partially) autonomoussensors 100 from the field of the “Internet of Things” with focus oncost reduction and/or large quantities.

The exemplary embodiments described and shown in the figures have beenselected merely by way of example. Different exemplary embodiments maybe combined with one another completely or in respect of individualfeatures. An exemplary embodiment may also be supplemented by featuresof a further exemplary embodiment. Furthermore, method steps accordingto the invention can be repeated and performed in an order other thanthat described. If an exemplary embodiment includes an “and/or” linkbetween a first feature and a second feature, this is thus to be readsuch that the exemplary embodiment in accordance with one embodimentincludes both the first feature and the second feature and in accordancewith a further embodiment includes either only the first feature or onlythe second feature.

1. A sensor comprising: a sensor element configured to provide a sensorsignal representing at least one measurand detected by the sensorelement; an electrical circuit configured to process the sensor signalto form a data signal; a photovoltaic cell configured to provideelectrical energy for the sensor element and the electrical circuit; anda housing, in which the sensor element, the electrical circuit and thephotovoltaic cell are positioned, the housing including a recess inwhich the photovoltaic cell is positioned, and a rim surrounding therecess and protruding beyond the photovoltaic cell.
 2. The sensor asclaimed in claim 1, further comprising an edge of the housing formedfrom a printed circuit board material or from a potting compound.
 3. Thesensor as claimed in claim 1, further comprising a junction regionbetween the photovoltaic cell and the housing that is sealed in a regionof a solar-active surface of the photovoltaic cell with a protectivemedium that is at least partially transparent to solar radiation.
 4. Thesensor as claimed in claim 1, the sensor element and/or the electricalcircuit being positioned on a light-insensitive side of the photovoltaiccell.
 5. The sensor as claimed in claim 1, wherein the housing is formedat least in part by a potting compound and the sensor element and/or theelectrical circuit is potted at least partially in the potting compound.6. The sensor as claimed in claim 1, further comprising electricalconductor tracks positioned in the rim of the housing, wherein thephotovoltaic cell is electrically contacted in the rim at least on oneside by the conductive tracks by feedthroughs.
 7. The sensor as claimedin claim 1, wherein the photovoltaic cell is surrounded by the rim suchthat there is contact at least on all sides with the surfaces of thephotovoltaic cell, at least in sub-regions of the surfaces.
 8. Thesensor as claimed in claim 1, wherein a solar-active side of thephotovoltaic cell is covered at least in part by the rim.
 9. The sensoras claimed in claim 1, further comprising electrical connectors of thehousing on the rim and/or on a rear side of the housing opposite therecess.
 10. A method for producing a sensor comprising: providing asensor element, an electrical circuit and a photovoltaic cell, thephotovoltaic cell being connected to the electrical circuit and theelectrical circuit being connected to the sensor element; andpositioning the sensor element, the electrical circuit and thephotovoltaic cell in a housing, the photovoltaic cell being positionedin a recess in the housing, wherein a rim of the housing surrounds therecess and protrudes beyond the photovoltaic cell.
 11. A methodcomprising: providing a plurality of arrangements formed of a sensorelement, an electrical circuit and a photovoltaic cell, wherein thephotovoltaic cell of each arrangement is connected to a respectiveelectrical circuit of each arrangement, and the electrical circuit ofeach arrangement is connected a respective sensor element of eacharrangement; positioning each of the plurality of arrangements in acommon housing; and separating the housing into a plurality ofsub-housings, wherein each sub-housing one of the plurality ofarrangements.